The present invention relates generally to communications in a wireless network and, more particularly, to the dynamic management of data in a wireless local area network (WLAN).
In certain networked environments, such as medical facility networks involving patient monitoring over WLANs, it is desirable to leverage an existing investment in a common network to deploy wireless bedside and telemetry applications. However, as more and more wireless clients access the WLAN, the network may become congested, with different types of devices competing for priority on the WLAN. Such interference and increased usage from multiple devices in wireless bands degrades overall network performance and can lead to gaps in critical patient data and dropouts or delays in delivering alarms that can impact patient safety. For example, a patient-worn telemetry device set up to monitor a high-acuity patient for potentially life-threatening arrhythmia may be transmitting data on the WLAN, but may not be equipped with a local alarm to alert caregivers to a change in the patient's condition. It is critical that the patient data and alarm messages from such a device be routed to, for example, a remote central monitoring station or portable electronic device carried by a caregiver in real-time over the WLAN. There may also be multiple bedside monitors competing for access to the WLAN that, by contrast, may be equipped with local alarms to alert caregivers to a change in conditions, such that any delay in transmission of an alarm on the network may not be as critical to patient safety. Furthermore, the respective acuity levels of the various patients being monitored by the various wireless monitoring devices on the WLAN may be constantly changing, and the delay of data from a lower-acuity patient being monitored by a patient-worn telemetry device may not be as critical to patient safety as a delay of data from a higher-acuity patient. In the absence of effective means for prioritizing transmission of the patient data and alarm messages among these various devices, the more critical data may be delayed or lost.
The Institute of Electronic and Electrical Engineers (IEEE) 802.11 standard for wireless LANs is a popular mechanism for setting up networks in many industrial, office, home and medical environments. The main limitation of the legacy 802.11 is that it cannot support priority classifications to differentiate among different types of traffic. That is, every type of traffic is treated with equal fairness in the network. A newer standard called 802.11e has emerged which has prioritized traffic delivery for differentiating among traffic at different levels of criticality. The 802.11e standard achieves this by having a differentiated services control parameter in the IP layer for controlling wireless communication. For example, a six-bit Differentiated Services Code Point (DCSP) may be assigned at the IP layer and used in the MAC layer to classify and prioritize types of traffic. Using the DSCP parameter for lower and higher priority traffic classes, the higher priority traffic class is assigned shorter wait times for transmission across the WLAN. However, even though 802.11e can differentiate among traffic classes, under standard operating conditions, the 802.11e DSCP parameter is static in nature, meaning that it is not optimal under all monitoring scenarios. For example, when a change in the status or condition of a patient being monitored over a medical facility WLAN occurs, the 802.11e DSCP parameter does not adapt to those changing conditions. This makes the 802.11e DSCP default parameters unsuitable for some applications, such devices used for patient monitoring in a medical facility, where dropouts and delays in delivering alarms can impact patient safety.
Furthermore, as noted above, there may be circumstances under which the signal quality of the WLAN degrades, causing the connected data rate of wireless clients accessing the WLAN to drop. When connected at the lower data rate, it takes longer for an individual wireless client to send its data and may result in lost data, delayed alarms or gaps in waveforms. Currently, wireless clients such as medical monitoring devices may often need to transmit several different types of data, depending on the particular monitoring scenario. However, in the absence of effective means for the wireless client to manage the size of its data payload, the more critical data may be delayed or lost when interference and increased usage from multiple devices in wireless bands degrades overall network performance.
Accordingly, there is need for improved systems, devices and methods of data prioritization to increase the reliability of data transmission over WLANs and to ensure robust transmission of critical data, such as patient data in medical monitoring applications.